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INFO: rcu detected stall in sys_mprotect (2)

Status: upstream: reported syz repro on 2025/12/14 03:47
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+5d7bb221a7b75f9747e2@syzkaller.appspotmail.com
First crash: 48d, last: 32d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/12/30 linux-6.6.y (ToT) 5fa4793a2d2d syz [report] INFO: rcu detected stall in corrupted
2025/12/30 upstream (ToT) 8640b74557fc syz Didn't crash
▶ ▼ Similar bugs (16)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_mprotect (6) kernel 1 3 1115d 1166d 0/29 auto-obsoleted due to no activity on 2023/04/20 15:51
upstream INFO: rcu detected stall in sys_mprotect (3) mm 1 3 2215d 2215d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in sys_mprotect (2) mm 1 1 2215d 2215d 0/29 closed as invalid on 2020/01/08 05:23
upstream INFO: rcu detected stall in sys_mprotect (8) mm 1 syz done 96 24d 477d 0/29 upstream: reported syz repro on 2024/10/11 07:05
linux-5.15 INFO: rcu detected stall in sys_mprotect 1 1 645d 645d 0/3 auto-obsoleted due to no activity on 2024/08/04 17:12
linux-6.6 INFO: rcu detected stall in sys_mprotect 1 1 169d 169d 0/2 auto-obsoleted due to no activity on 2025/11/23 01:57
upstream INFO: rcu detected stall in sys_mprotect (5) kernel 1 1 1433d 1433d 0/29 auto-closed as invalid on 2022/05/29 03:15
linux-5.15 INFO: rcu detected stall in sys_mprotect (3) 1 1 95d 95d 0/3 upstream: reported on 2025/10/28 12:28
linux-6.1 INFO: rcu detected stall in sys_mprotect (3) 1 8 3d22h 134d 0/3 upstream: reported on 2025/09/19 07:33
upstream INFO: rcu detected stall in sys_mprotect (4) mm 1 1 1498d 1498d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in sys_mprotect mm 1 3 2251d 2251d 0/29 closed as invalid on 2019/12/04 14:04
linux-5.15 INFO: rcu detected stall in sys_mprotect (2) 1 1 199d 199d 0/3 auto-obsoleted due to no activity on 2025/10/24 12:50
upstream INFO: rcu detected stall in sys_mprotect (7) mm 1 9 745d 973d 0/29 auto-obsoleted due to no activity on 2024/04/15 19:55
linux-6.1 INFO: rcu detected stall in sys_mprotect (2) 1 1 370d 370d 0/3 auto-obsoleted due to no activity on 2025/05/06 08:25
linux-6.1 INFO: rcu detected stall in sys_mprotect 1 7 541d 617d 0/3 auto-obsoleted due to no activity on 2024/11/16 09:36
android-5-15 BUG: soft lockup in sys_mprotect 1 1 612d 612d 0/2 auto-obsoleted due to no activity on 2024/08/27 08:23
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/01/23 20:56 1m fix candidate upstream error job log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6156/1:b..l P6070/1:b..l P6223/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=14817, q=836 ncpus=2)
task:modprobe        state:R  running task     stack:24232 pid:6223  ppid:2957   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:get_current arch/x86/include/asm/current.h:41 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x60 kernel/kcov.c:215
Code: 00 00 f3 0f 1e fa 53 48 89 fb e8 13 00 00 00 48 8b 3d 9c 92 c4 0c 48 89 de 5b e9 43 9d 56 00 cc cc cc f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d f0 24 7e 7e 65 8b 15 f1 24 7e 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc90003c27778 EFLAGS: 00000293
RAX: ffffffff8a553b54 RBX: 0000000000000004 RCX: ffff88802d240000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003c27950 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff2e5551c R12: 0000000000000000
R13: ffffc90003c278a0 R14: ffff888077507a00 R15: ffff888077507ac0
 mas_validate_gaps lib/maple_tree.c:6998 [inline]
 mt_validate+0x2e54/0x4530 lib/maple_tree.c:7234
 validate_mm+0xb1/0x420 mm/mmap.c:288
 __split_vma+0xa93/0xc00 mm/mmap.c:2425
 mprotect_fixup+0xaad/0xc90 mm/mprotect.c:650
 do_mprotect_pkey+0x76e/0xc30 mm/mprotect.c:819
 __do_sys_mprotect mm/mprotect.c:840 [inline]
 __se_sys_mprotect mm/mprotect.c:837 [inline]
 __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:837
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f03d0bfd2c7
RSP: 002b:00007ffe152ab178 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 00007f03d0bd95f0 RCX: 00007f03d0bfd2c7
RDX: 0000000000000001 RSI: 0000000000004000 RDI: 00007f03d0b04000
RBP: 00007ffe152ab440 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f03d0bd95f0 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
task:kworker/u4:12   state:R  running task     stack:25288 pid:6070  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_acquire+0x1f2/0x410 kernel/locking/lockdep.c:5758
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00
RSP: 0018:ffffc900046d79c0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 715d0a53a9244200
RDX: 0000000000000000 RSI: ffffffff8aaace60 RDI: ffffffff8afc6f80
RBP: ffffc900046d7ad8 R08: dffffc0000000000 R09: 1ffffffff21b28a0
R10: dffffc0000000000 R11: fffffbfff21b28a1 R12: 1ffff920008daf44
R13: ffffffff8cd2ff20 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 batadv_nc_process_nc_paths+0xdb/0x390 net/batman-adv/network-coding.c:687
 batadv_nc_worker+0x429/0x610 net/batman-adv/network-coding.c:728
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
task:udevd           state:R  running task     stack:27272 pid:6156  ppid:5138   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0xfa/0x110 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x11f/0x190 kernel/sched/wait.c:213
 sock_def_readable+0x1e1/0x430 net/core/sock.c:3354
 unix_dgram_sendmsg+0x10cc/0x1720 net/unix/af_unix.c:2141
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 sock_write_iter+0x2bb/0x3f0 net/socket.c:1160
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x43b/0x940 fs/read_write.c:584
 ksys_write+0x147/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd7536a7407
RSP: 002b:00007ffca524cd30 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd753e4e880 RCX: 00007fd7536a7407
RDX: 0000000000000000 RSI: 00007ffca524cdd7 RDI: 000000000000000a
RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007fd753e4e6e8
R13: 0000000000000000 R14: 0000000000000000 R15: 0000563d368a6320
 </TASK>
rcu: rcu_preempt kthread starved for 10593 jiffies! g14817 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27752 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 6224 Comm: syz.4.28 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:lockdep_hardirqs_on_prepare+0x66/0x760 kernel/locking/lockdep.c:4313
Code: 41 48 c7 44 24 28 27 66 77 8c 48 c7 44 24 30 a0 c1 66 81 48 8d 5c 24 20 48 c1 eb 03 48 b8 f1 f1 f1 f1 00 f3 f3 f3 48 89 04 13 <48> c7 c0 ec 55 4a 8e 48 c1 e8 03 0f b6 04 10 84 c0 0f 85 2a 05 00
RSP: 0018:ffffc90003c57e40 EFLAGS: 00000806
RAX: f3f3f300f1f1f1f1 RBX: 1ffff9200078afcc RCX: 9d2f9cd658565b00
RDX: dffffc0000000000 RSI: ffffffff8afc6f60 RDI: ffffffff8afc6f20
RBP: ffffc90003c57f00 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: 0000000000000000
R13: 0000000000000000 R14: ffffc90003c57f58 R15: 000000000000000f
FS:  000055555f93b500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33f63fff CR3: 000000002c324000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 __exit_to_user_mode kernel/entry/common.c:137 [inline]
 syscall_exit_to_user_mode+0x24/0x50 kernel/entry/common.c:304
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f0f8364d6e0
Code: 44 24 20 0f 29 44 24 30 0f 29 44 24 40 48 8b 44 24 08 ff d0 48 83 c4 50 31 c0 5b 5d 41 5c 41 5d 41 5e c3 0f 1f 80 00 00 00 00 <c3> 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 c3 66 66 2e 0f 1f
RSP: 002b:00007ffe3dad4d78 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007f0f839e5fa0 RCX: 00007f0f8378f749
RDX: 00007ffe3dad4d80 RSI: 00007ffe3dad4eb0 RDI: 0000000000000011
RBP: 00007f0f83813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0f839e5fa0 R14: 00007f0f839e5fa0 R15: 0000000000000004
 </TASK>
sched: RT throttling activated

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/30 06:01 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_mprotect
2025/12/17 11:30 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_mprotect
2025/12/14 03:47 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_mprotect
* Struck through repros no longer work on HEAD.